New services are constantly being made available with the development of telecommunication networks and also that of the Internet. A new impetus for the emergence of new services has resulted from the convergence of packet-based networks with circuit-based networks, such as the traditional Public Switched Telephone Network (PSTN).
It can be observed that the traditional distinction between circuit-based networks—being at the core of traditional telecommunications—and packet-based networks which are at the heart of the Internet network, is disappearing. In the latest developments, the concept of session is being integrated into packet-based networks. Many applications and new services which are available to customers—and also those which will be offered in the near future—are based on the creation and the management of a session. Such a session allows an exchange of data between different participants who are reachable through their address and who can communicate through a wide range of different terminals, such as personal computers, Personal Document Assistant (PDA), portable computers, cellular telephones, fixed telephones, Universal Mobile Telecommunications System (UTMS) terminals, for instance.
Substantial research and investigations have been carried out in order to define the concept of session in the traditional Internet network. Some of this work was carried out within the frame of the Internet Engineering Task Force (IETF) and have lead to the Session Initiation Protocol (SIP) which ties together the PSTN and the Internet.
SIP is the core protocol enabling the setting up of conferencing, telephony, multimedia and other types of communication sessions on the Internet. It is expected to be at the heart of future high-quality voice sessions over packet networks, including wireless networks. With the development of the SIP protocol, there is provided the possibility of real time multimedia sessions, including voice, video and data.
More information concerning the SIP protocol can be found in RFC 3261 “SIP: Session Initiation Protocol”. Extensions to SIP are being provided within the IETF in http://www.ietf.org/ids.by.wg/sip.html
As a wider variety of telecommunications services are offered to customers of the era of information, including services based on the Web, multimedia services involving video and audio streaming, more and more attention is being directed to the general problem of the Quality of Service (QoS).
Traditional Internet service providers and, more generally, the companies handling the telecommunication networks have already at least partially addressed the problem of measuring the actual quality of service offered to their customers and, therefore, some techniques are already known.
A first technique, illustrated in FIG. 1, is based on the use of a passive probe 3 which is piece of specialized equipment that is installed between two particular communicating nodes 1 and 2 within a network 10. Such a passive probe is designed to monitor the traffic between the two nodes. By observing a certain number of parameters, and particularly the loss of packets, passive probe 3 can track the quality of the communication and can report a QoS measure to the service provider.
A second technique is based on the use of an active probe, such as active probe 4 of FIG. 2 which—contrary to the passive probes—is designed to generate additional traffic and behave like an end-user generating traffic. For this reason, such active probes are also called end-user simulators which can, again, be used for tracking the quality of service of the communication as the packets are being conveyed throughout the network.
A third technique which is also known to the service operators involves processing the information provided by standard management interfaces (log files for Standard Network Management Protocols, for instance) in the network and which are constantly updated.
While the known techniques do provide means to measure the quality of service within a communication network, they are generally reserved for use by service or network operators. They cannot normally be used at the level of the user who, certainly, may have a strong interest in determining the precise measurement of the quality of service which they are experiencing, and for which they will be charged.